SQLite

** The pager is used to access a database disk file.  It implements
** atomic commit and rollback through the use of a journal file that
** is separate from the database file.  The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.567 2009/02/12 09:11:56 danielk1977 Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"

/*
** Macros for troubleshooting.  Normally turned off
*/

** If this is a savepoint rollback, then memory may have to be dynamically
** allocated by this function. If this is the case and an allocation fails,
** SQLITE_NOMEM is returned.
*/
static int pager_playback_one_page(
  Pager *pPager,                /* The pager being played back */
  int isMainJrnl,               /* 1 -> main journal. 0 -> sub-journal. */
  int isUnsync,                 /* True if reading from unsynced main journal */
  i64 *pOffset,                 /* Offset of record to playback */
  int isSavepnt,                /* True for a savepoint rollback */
  Bitvec *pDone                 /* Bitvec of pages already played back */
){
  int rc;
  PgHdr *pPg;                   /* An existing page in the cache */
  Pgno pgno;                    /* The page number of a page in journal */

  PAGERTRACE(("PLAYBACK %d page %d hash(%08x) %s\n",
               PAGERID(pPager), pgno, pager_datahash(pPager->pageSize, aData),
               (isMainJrnl?"main-journal":"sub-journal")
  ));
  if( (pPager->state>=PAGER_EXCLUSIVE)
   && (pPg==0 || 0==(pPg->flags&PGHDR_NEED_SYNC))
   && isOpen(pPager->fd)
   && !isUnsync
  ){
    i64 ofst = (pgno-1)*(i64)pPager->pageSize;
    rc = sqlite3OsWrite(pPager->fd, aData, pPager->pageSize, ofst);
    if( pgno>pPager->dbFileSize ){
      pPager->dbFileSize = pgno;
    }
    sqlite3BackupUpdate(pPager->pBackup, pgno, aData);

  needPagerReset = isHot;

  /* This loop terminates either when a readJournalHdr() or 
  ** pager_playback_one_page() call returns SQLITE_DONE or an IO error 
  ** occurs. 
  */
  while( 1 ){
    int isUnsync = 0;

    /* Read the next journal header from the journal file.  If there are
    ** not enough bytes left in the journal file for a complete header, or
    ** it is corrupted, then a process must of failed while writing it.
    ** This indicates nothing more needs to be rolled back.
    */
    rc = readJournalHdr(pPager, szJ, &nRec, &mxPg);

         && pPager->journalHdr+JOURNAL_HDR_SZ(pPager)!=pPager->journalOff
         && ((szJ - pPager->journalOff) / JOURNAL_PG_SZ(pPager))>0
         && pagerNextJournalPageIsValid(pPager)
    );
    if( nRec==0 && !isHot &&
        pPager->journalHdr+JOURNAL_HDR_SZ(pPager)==pPager->journalOff ){
      nRec = (int)((szJ - pPager->journalOff) / JOURNAL_PG_SZ(pPager));
      isUnsync = 1;
    }

    /* If this is the first header read from the journal, truncate the
    ** database file back to its original size.
    */
    if( pPager->journalOff==JOURNAL_HDR_SZ(pPager) ){
      rc = pager_truncate(pPager, mxPg);

    ** database file and/or page cache.
    */
    for(u=0; u<nRec; u++){
      if( needPagerReset ){
        pager_reset(pPager);
        needPagerReset = 0;
      }
      rc = pager_playback_one_page(pPager,1,isUnsync,&pPager->journalOff,0,0);
      if( rc!=SQLITE_OK ){
        if( rc==SQLITE_DONE ){
          rc = SQLITE_OK;
          pPager->journalOff = szJ;
          break;
        }else{
          /* If we are unable to rollback, then the database is probably

  ** will be skipped automatically.  Pages are added to pDone as they
  ** are played back.
  */
  if( pSavepoint ){
    iHdrOff = pSavepoint->iHdrOffset ? pSavepoint->iHdrOffset : szJ;
    pPager->journalOff = pSavepoint->iOffset;
    while( rc==SQLITE_OK && pPager->journalOff<iHdrOff ){
      rc = pager_playback_one_page(pPager, 1, 0, &pPager->journalOff, 1, pDone);
    }
    assert( rc!=SQLITE_DONE );
  }else{
    pPager->journalOff = 0;
  }

  /* Continue rolling back records out of the main journal starting at

    );
    if( nJRec==0 
     && pPager->journalHdr+JOURNAL_HDR_SZ(pPager)==pPager->journalOff
    ){
      nJRec = (u32)((szJ - pPager->journalOff)/JOURNAL_PG_SZ(pPager));
    }
    for(ii=0; rc==SQLITE_OK && ii<nJRec && pPager->journalOff<szJ; ii++){
      rc = pager_playback_one_page(pPager, 1, 0, &pPager->journalOff, 1, pDone);
    }
    assert( rc!=SQLITE_DONE );
  }
  assert( rc!=SQLITE_OK || pPager->journalOff==szJ );

  /* Finally,  rollback pages from the sub-journal.  Page that were
  ** previously rolled back out of the main journal (and are hence in pDone)
  ** will be skipped.  Out-of-range pages are also skipped.
  */
  if( pSavepoint ){
    u32 ii;            /* Loop counter */
    i64 offset = pSavepoint->iSubRec*(4+pPager->pageSize);
    for(ii=pSavepoint->iSubRec; rc==SQLITE_OK && ii<pPager->nSubRec; ii++){
      assert( offset==ii*(4+pPager->pageSize) );
      rc = pager_playback_one_page(pPager, 0, 0, &offset, 1, pDone);
    }
    assert( rc!=SQLITE_DONE );
  }

  sqlite3BitvecDestroy(pDone);
  if( rc==SQLITE_OK ){
    pPager->journalOff = szJ;

******************************************************************************
**
** This file contains code for a VFS layer that acts as a wrapper around
** an existing VFS. The code in this file attempts to verify that SQLite
** correctly populates and syncs a journal file before writing to a
** corresponding database file.
**
** $Id: test_journal.c,v 1.11 2009/02/12 09:11:56 danielk1977 Exp $
*/
#if SQLITE_TEST          /* This file is used for testing only */

#include "sqlite3.h"
#include "sqliteInt.h"

/*

};

struct JtGlobal {
  sqlite3_vfs *pVfs;             /* Parent VFS */
  jt_file *pList;                /* List of all open files */
};
static struct JtGlobal g = {0, 0};

extern int sqlite3_io_error_pending;
static void stop_ioerr_simulation(int *piSave){
  *piSave = sqlite3_io_error_pending;
  sqlite3_io_error_pending = -1;
}
static void start_ioerr_simulation(int iSave){
  sqlite3_io_error_pending = iSave;
}

/*
** The jt_file pointed to by the argument may or may not be a file-handle
** open on a main database file. If it is, and a transaction is currently
** opened on the file, then discard all transaction related data.
*/
static void closeTransaction(jt_file *p){

  pMain->aCksum = sqlite3_malloc(sizeof(u32) * (pMain->nPage + 1));
  pJournal->iMaxOff = 0;

  if( !pMain->pWritable || !pMain->aCksum || !aData ){
    rc = SQLITE_IOERR_NOMEM;
  }else if( pMain->nPage>0 ){
    u32 iTrunk;
    int iSave;

    stop_ioerr_simulation(&iSave);

    /* Read the database free-list. Add the page-number for each free-list
    ** leaf to the jt_file.pWritable bitvec.
    */
    rc = sqlite3OsRead(p, aData, pMain->nPagesize, 0);
    iTrunk = decodeUint32(&aData[32]);
    while( rc==SQLITE_OK && iTrunk>0 ){

      for(ii=0; rc==SQLITE_OK && ii<pMain->nPage; ii++){
        i64 iOff = (i64)(pMain->nPagesize) * (i64)ii;
        if( iOff==PENDING_BYTE ) continue;
        rc = sqlite3OsRead(pMain->pReal, aData, pMain->nPagesize, iOff);
        pMain->aCksum[ii] = genCksum(aData, pMain->nPagesize);
      }
    }

    start_ioerr_simulation(iSave);
  }

  sqlite3_free(aData);
  return rc;
}

/*

static int readJournalFile(jt_file *p, jt_file *pMain){
  int rc = SQLITE_OK;
  unsigned char zBuf[28];
  sqlite3_file *pReal = p->pReal;
  sqlite3_int64 iOff = 0;
  sqlite3_int64 iSize = p->iMaxOff;
  unsigned char *aPage;
  int iSave;

  aPage = sqlite3_malloc(pMain->nPagesize);
  if( !aPage ){
    return SQLITE_IOERR_NOMEM;
  }

  stop_ioerr_simulation(&iSave);

  while( rc==SQLITE_OK && iOff<iSize ){
    u32 nRec, nPage, nSector, nPagesize;
    u32 ii;

    /* Read and decode the next journal-header from the journal file. */
    rc = sqlite3OsRead(pReal, zBuf, 28, iOff);

      }
    }

    iOff = ((iOff + (nSector-1)) / nSector) * nSector;
  }

finish_rjf:
  start_ioerr_simulation(iSave);
  sqlite3_free(aPage);
  if( rc==SQLITE_IOERR_SHORT_READ ){
    rc = SQLITE_OK;
  }
  return rc;
}

# This file implements regression tests for SQLite library.  The
# focus of this file is testing for correct handling of I/O errors
# such as writes failing because the disk is full.
# 
# The tests in this file use special facilities that are only
# available in the SQLite test fixture.
#
# $Id: ioerr2.test,v 1.11 2009/02/12 09:11:56 danielk1977 Exp $

set testdir [file dirname $argv0]
source $testdir/tester.tcl

ifcapable !integrityck {
  finish_test
  return

  #
  do_test ioerr2-6 {
    set ::sqlite_io_error_hit 0
    set ::sqlite_io_error_pending 1
    catchsql {PRAGMA temp_store_directory = '/tmp/'}
  } {1 {not a writable directory}}
}

do_ioerr_test ioerr2-7 -persist 0 -sqlprep {
  PRAGMA cache_size = 10;
  PRAGMA auto_vacuum = 1;
  CREATE TABLE ab(a, b);
  CREATE TABLE de(d, e);
  INSERT INTO ab VALUES(1, randstr(200,200));
  INSERT INTO ab SELECT a+1, randstr(200,200) FROM ab;
  INSERT INTO ab SELECT a+2, randstr(200,200) FROM ab;
  INSERT INTO ab SELECT a+4, randstr(200,200) FROM ab;
  INSERT INTO ab SELECT a+8, randstr(200,200) FROM ab;
  INSERT INTO ab SELECT a+16, randstr(200,200) FROM ab;
  INSERT INTO ab SELECT a+32, randstr(200,200) FROM ab;
  INSERT INTO ab SELECT a+64, randstr(200,200) FROM ab;
  INSERT INTO de SELECT * FROM ab;
} -sqlbody {
  BEGIN;
  UPDATE ab SET b = randstr(200,200);
  UPDATE de SET e = randstr(200,200) WHERE d = (SELECT max(d) FROM de);
  DELETE FROM ab;
  COMMIT;
}

finish_test